AEG-Source-Mercenaries for the qualities Laminated and serrated for metal weapons. Laminated Steel-Gains +1 damage to all its rolls and its critical hit multiplier goes up by one as well. Furthermore, the weapon gains +5 to its normal hardness. Cost 900 and the DC to create is 23. Serrated Weapons-Has its critical threat range increased by +1.
Costs 300 and DC is 20. If you're playing with flaws you have two more feats for two flaws.

Laminated only applyes to slashing only weapons if your weapons dose other damage you cannot use this construction type

The signature weapon from Kensai creates a single weapon in which the Kensai is known for (not two, but you can have a double weapon that can seperate) with four levels of Kensai you can give it a total bonus of +4 with the expendature of 640 exp (for a double weapon you need to spend it twice for each end) I put sonic burst and speed to give me a total +4 enhancement bonus on my weapon(remember you need to do this twice for a double weapon. Speed does not stack either). Dwarven Blackrock DR Category Adamantine, (Godsteel) Melee mod to hit +3 Dmg 2 sizes larger Threat +1 Crit +1 + Crit Mult 1 hardness 30 hit points +10 weight +10% +1600gp/lb (3 lb. Minimum)
All bonuses are MW; ignores up to 30 hardness vs. objects; immune to rust; item has best properties of steel or stone

SO the attacks work out to be something like this..... 2 for < +5 BAB, +1 for two weapon fighting, +1 in off hand for improved two weapon fighting with a -5, +1 at the highest BAB for speed making it five attacks. The attack bonus goes something like this 8(BAB)+1(weapon focus)+1(weapon enhancement)+4(str)+1(aptitude)= +15/+15(speed)/+13(twf)/+10/+5(ITWF). if black rock is allowed it goes like this=8(BAB)+1(weapon focus)+1(weapon enhancement)+4(str)+3(black rock)+1(aptitude)=+18/+18(speed)/+16(twf)/+13/+8(ITWF). Damage and criticals are enhanced to this= DAMAGE d6 + 4(str)+2 (Weapon Spec), +1 (magical enhancement) +d6 (sonic)+1 (lamanted)+1(aptitude)= 2d6+9 with a critical of 12-20 (18-20 base +1 serrated 17-20, improved critical for light mace 13-20 with a X3 crit mod(X2 +1 lamanted +1 improved critical d&D math 2+2=3). With Godsteel it breaks down to this DAMAGE 2d6(blackrock treats weapons as 2 cat sizes larger)+d6 (sonic))+2 (Weapon Spec), +1 (magical enhancement)+1(lamanted)+1(aptitude)= 3d6+9 and Critical on 12-20 (18-20 base +1 serrated 17-20,+1(godsteel)16-20, improved critical for light mace 11-20 with a crit mod of X3.5 (X2 +1 lamanted +1 improved critical+1 god steel d&D math 2+3=3.5). Again thats is with godsteel.
Aptitude says Aptitude weapon special ability in tomb of battle +1 bonus cost
A wielder who has feats that affect the use of a particular type of weapon, such as Weapon Focus, Greater Weapon Focus, Weapon Specialization, or the like, can apply the benefits of those feats to any weapon that has the aptitude quality. In addition, if any of the wielder’s weapon use feats are specifically keyed to the aptitude weapon’s type, he gains a +1 bonus on attack and damage rolls.
For this build the scimitars act like light maces for feats. Lightning Mace states Whenever you roll a threat on an attack roll while using a light mace in each hand, you gain an additional attack at that same attack bonus. So if you can hit (you still need to hit whatever your hitting) you crit about 50% of the time by 9th level and if you crit on the first swing you can keep critting due to lightnong mace.

Just try and get a cloak of resistance to help with saves and good armor.

Take a level of Monk train in Overwhelming Attack style (Unearthed Arcana) to get improved unarmed strike and power attack. Use these to get Roundabout Kick (Complete Warrior). The wording on the Aptitude weapon effect text doesn't say that you can't use feats for multiple weapon types (say maces and unarmed).